The measurement of speed of an individual railcar in a moving train proximate to a bulk material processing station is not addressed by existing systems. Bulk material processing, including loading, unloading, and/or cargo spray treatments, etc., involving a moving railcar requires extreme precision to avoid inefficiencies, errors and/or wastage. Where the control center/station is electronically connected to an associated bulk material processing device adapted for kinetic as opposed to static operations, loading/unloading/coating application, etc., waste and inefficiencies result from assuming vehicle speed. For example, when the speed of a railcar is estimated or assumed, it may be overloaded resulting in spillage if it passes too slowly through a loading facility. Correspondingly, when the estimated speed is too slow of a filled hopper railcar passing through a special application station, e.g., spraying a latex surfactant dust suppressant or anti-freeze/freeze-proofing material on a railcar/content, the spraying will be incomplete as the terminal portion of the bulk material vehicle/load will not be coated. Such incomplete applications may result in unnecessary labor to remove frozen material and/or even lead to violations of applicable transportation regulations. Conversely, if the assumed speed varies in the context of loading, a vehicle may be overloaded, under loaded, or unevenly distributed. In the context of applying additives, additives may be wasted or placed imprecisely (economically and environmentally undesirable). The invention maximizes efficiencies of such operations by determination of the specific target railcar speed rather than generalizing across the entire train.
The prior art contains numerous examples of speed and directional sensing systems based on discrete sensors, such as photo-eyes or rail track switches, However, such systems due to sensor spacing, can only update such information periodically. While this method of measuring speed is somewhat reasonable for overall or general speed determination, such systems are inadequate to make real-time speed determinations during critical stages. More specifically, reliance on sets of static discrete sensors (usually photoelectric sensors or track mounted switches) installed at known distances from each other may not be accurate when a railcar stops or is subject to speed irregularities between two sensors. Even reliance on sophisticated computers, e.g., a PLC (Programmable Logic Controller) control system that monitor the on/off state of the static sensors and calculate the time elapsed between subsequent sensor on/off states to process the periodic data does not overcome the real-time detection issue.
Such a situation can be problematic particularly in cases such as when the measured speed information is provided to a flow control device or a loading chute in a bulk material processing station. One technique employed to overcome this negative consequence is to populate the system with more detectors. By adding additional static sensors to the sensor array, the ‘resolution’ of the system is increased and the speed determination errors correspondingly minimized. But such a “solution” introduces additional infrastructure needs in wiring, sensors, PLC control points, etc. such that the system becomes expensive, difficult to operate, and requires considerably labor to maintain. Furthermore, although to a lesser extent, such a periodic sensing array still possesses similar limitations to those described above.
Another approach to measure train speed is based on Doppler shift-technology (e.g., police radar). However, at sub-5 miles per hour speeds typically associated with bulk material processing operations, Doppler shift detection is neither meaningfully measurable nor capable of providing the required accuracy for vehicle speed detection. This is attributable to the virtually non-existent Doppler shift at low speeds at typical approved frequencies. Consequently, in the context of bulk material transport and processing equipment (loaders, unloaders, sprayers, etc.), particularly in the case of a slow moving train of coupled railcars, such conventional speed measuring devices are ineffective and not reliably usable for vehicle/bulk material processing equipment coordination.
Other conventional approaches utilized for determining the speed of railcars in a moving unit train include satellite GPS tracking and on-board, stationary electro-mechanical devices. An example of a locomotive-mounted, onboard electromechanical, device is described in U.S. Pat. No. 3,779,086 (a locomotive drive-truck-mounted pulse generator speed and distance measurement device). An example of a more modem GPS based system is described in U.S. Pat. No. 7,610,152 (a train-mounted navigator geo-positional receiver solution combined with track database information). Neither of these prior art systems are capable of determining the specific velocity of an individual railcar within a long train where such velocity can vary at any discrete point in time due to train stretching (tension) or bunching (compression) effects caused, for example, by coupler slack considerations. Therefore, locomotive or whole train based speed determination whether from a vehicle mounted device or remote tracking device, e.g., GPS, are not sufficiently applicable or accurate for usage during critical stages of bulk material processing operations.
The final prior art approach for railcar speed measurement described herein is based on laser detection (LIDAR). The Stalker Laser from Applied Technologies, Inc. is reported to provide laser speed measurement at a range up to 4000 feet with reported 0.2 mph sensitivity. While representing an improvement, this system does not address the specific problem associated precise speed measurement of an individual rail-car in a moving train associated with a bulk material processing station.
Thus there exists a need for a system and method to achieve precise and accurate, instantaneous, real time individual bulk material transport vehicle, and particularly, a railcar, speed measurement proximate to a bulk material processing station.